China
Africa
Explore chapters and articles related to this topic
Industrial minerals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
A thermal method of treating dolomite results in the reduction of magnesium oxide, produced by calcining the dolomite raw material, with ferrosilicon to produce metallic magnesium and a calcium iron silicate slag. The calcining step involves the heating of the crushed dolomite in a kiln to produce a mixture of magnesium and calcium oxides: MgCO3⋅CaCO3(s)→MgO⋅CaO(s)+2CO2(g) Reduction of the magnesium oxide is done in the second step. Ferrosilicon is the reducing agent. The ferrosilicon is an alloy of iron and silicon made by heating sand with coke and scraps of iron.
Ferroalloys Waste Production and Utilization
Published in Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde, Waste Production and Utilization in the Metal Extraction Industry, 2017
Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde
The raw materials and process requirements in the generic production of silicon and ferrosilicon alloys were discussed in Sections 5.5.4.2 and 5.5.4.3, respectively. As already discussed in the preceding sections, ferrosilicon is typically an alloy of iron and silicon (Eric, 2014). In addition, carbon may be present in the ferrosilicon alloy as well, mainly as dissolved carbon and SiC particles (Eric, 2014). Although, in principle, the silicon and ferrosilicon production processes are similar, the fundamental difference is that iron-bearing materials in the form of high-quality iron ore and scrap are added as part of the charge in the ferrosilicon alloy process (Dosaj et al., 2005; Tangstad, 2013b; Eric, 2014). In essence, silicon-based ferroalloys are produced by the carbothermic reduction of quartz and/or quartzite and iron oxide materials in semi-open or closed submerged arc furnaces (Dosaj et al., 2005; Tangstad, 2013b; Eric, 2014). Specific requirements of the reductant materials in the ferrosilicon alloy process include (Tangstad, 2013b) (1) high electrical resistance (to enable smelting of charge due to resistance heating), (2) high reactivity in relation to SiO2 and SiO gas reduction and (3) constant moisture.
Production and Types of Condensed Silica Fume
Published in V. M. Malhotra, V. S. Ramachandran, R. F. Feldman, Pierre-Claude Aïtcin, Condensed Silica Fume in Concrete, 1987
V. M. Malhotra, V. S. Ramachandran, R. F. Feldman, Pierre-Claude Aïtcin
Silicon and ferrosilicon of various Si contents. Silicon metal; it is a metal grade containing more than 96% of siliconFerrosilicon 90% containing from 92 to 95% of siliconFerrosilicon 85% containing from 83 to 88% of siliconFerrosilicon 75% containing from 74 to 79% of silicon This type is probably the most widely produced alloy Ferrosilicon 65% containing from 65 to 70% of siliconFerrosilicon 50% containing from 47 to 51% of silicon This type of alloy is almost exclusively produced in the U.S. Ferrosilicon 22% containing from 22 to 24% of siliconFerrosilicon 15% containing from 14 to 17% of silicon
The impact resistance and mechanical properties of fiber reinforced self-compacting concrete (SCC) containing nano-SiO2 and silica fume
Published in European Journal of Environmental and Civil Engineering, 2018
Ordinary Portland cement 42.5R, crushed sand, fly ash, silica fume, viscosity modification agent (VMA), water, high-range water reducer agent with a water reduction from 10 to 15% in small dosage rates and achieving water reduction up to 30% at high dosage rates were used to adjust the workability of the SCC mixtures. Nano-silica is selected as pozzolanic material to be used in this study with average particle size of 15 nm and 45 m2/g Blaine fineness. Particle size of the crushed sand was distributed with a maximum grain diameter of approximately 4.75 mm, while the proportion of grains smaller than .1 mm was below 18%. The mixtures were prepared with the cement replacement by 0 or 1 wt% of SiO2 nanoparticles and 0 or 7 wt% of silica fume. Silica fume composed of submicron particles of silicon dioxide, is produced by electric arc furnace as a by-product of the production of metallic silicon or ferrosilicon alloys.
Thermodynamic model of metallothermic smelting of ferromolybdenum
Published in Mineral Processing and Extractive Metallurgy, 2019
Silicon is usually used in the form of ferrosilicon (75 wt-%Si), which has a composition close to [Fe.6Si]. Assuming that the additional iron required is supplied solely as metallic iron, then the equation for the production of 60 wt-% Mo (equimolar) alloy can be written as;The ED suggests that silicothermic reduction provides enough heat for a controllable reaction without additional heat supply. However, Habashi (1997) has noted that in practice the use of silicon as a reductant does not produce enough heat, due to heat losses, to melt both the slag and the alloy. The ED can be increased by replacing the added iron with iron ore Fe2O3;